# NTSB DCA25LA055: Boeing 787-9, N29975, Pacific Ocean, Hong Kong SAR China, December 3, 2024

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Class 4 · Limited · Final report
- Date: December 3, 2024, 22:30 local (22:30 UTC)
- Place: Pacific Ocean, Hong Kong SAR China · International waters
- Coordinates: 22.2203, 114.734
- Nearby events: https://openairdocs.org/map.md?lat=22.2203&lon=114.7340&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Defining event: [Enroute-descent: Turbulence encounter](https://openairdocs.org/ntsb-events/360)
- Highest injury: Serious injuries
- Injuries: 1 serious, 235 uninjured
- Status: Completed
- Report: Approved by Office Director
- Investigation class: Class 4 - Basic report with no Prelim publish
- NTSB office: Major Investigations Division
- Parties: United Airlines, Boeing, FAA
- NTSB case key (mKey): 199406
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DCA25LA055
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/199406/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=199406
- Page: https://openairdocs.org/ntsb/DCA25LA055

## Probable cause

An encounter with unexpected turbulence during descent.

## Findings

NTSB's coded findings; those marked are part of the probable cause.

- [Environmental issues](https://openairdocs.org/ntsb-findings/03020000): Environmental issues › Physical environment · Awareness of condition (probable cause); cases with it: [Boeing 787-9, 1 case](https://openairdocs.org/ntsb-findings/03020000/cases.md?model=1385609), [All aircraft, 24 cases](https://openairdocs.org/ntsb-findings/03020000/cases.md)
- [Environmental issues](https://openairdocs.org/ntsb-findings/03020000): Environmental issues › Physical environment · Effect on personnel (probable cause); cases with it: [Boeing 787-9, 1 case](https://openairdocs.org/ntsb-findings/03020000/cases.md?model=1385609), [All aircraft, 24 cases](https://openairdocs.org/ntsb-findings/03020000/cases.md)

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Enroute-descent: Turbulence encounter](https://openairdocs.org/ntsb-events/360) (defining event); cases with it: [Boeing 787-9, 5 cases](https://openairdocs.org/ntsb-events/360/sequence.md?model=1385609), [All aircraft, 423 cases](https://openairdocs.org/ntsb-events/360/sequence.md)

## Analysis

United Airlines flight 152 encountered moderate turbulence while descending through 10,000 feet to Hong Kong International Airport. As a result, a flight attendant (FA) sustained a serious injury. During the descent, the seatbelt sign was illuminated, and the flight crew had instructed the flight attendants to prepare for landing. The aircraft passed through a thin cloud layer at approximately 10,000 feet, followed by another cloud directly ahead. No radar returns were observed on the aircraft’s weather radar display and onboard weather applications showed no indications of an adverse ride. While passing through the top of the second cloud, the aircraft experienced about two seconds of moderate turbulence. The flight continued without further incident and landed uneventfully. After taxiing to the gate, the crew was informed that the number 4 FA was injured. At the time of the turbulence encounter, the number 4 FA was in the aft galley and was thrown to the floor, impacting her head, wrist, and buttocks. MedAire was consulted, and the FA was advised to seek medical evaluation upon arrival at the hotel. She was later transported to a local hospital, where she was diagnosed with a serious injury. At the time of the turbulence encounter, there were no active forecasts indicating turbulence in the area.

## Aircraft

- Registration: [N29975](https://openairdocs.org/aircraft/N29975), registered now, S/N 66134, built 2020 (OpenAirDocs)
- Reported make and model: BOEING 787-9
- Registry model: [Boeing 787-9](https://openairdocs.org/model/boeing-787-9) (registry code 1385609) (OpenAirDocs)
- Registry engine: [GE GENX-1B76A/P2](https://openairdocs.org/engine/ge-genx-1b76a-p2) (registry code 30231, turbo-fan) (OpenAirDocs)
- Category: Airplane
- Serial number: 66134
- Year built: 2020
- Airframe hours: 11522.55
- Engines: GE GENX-1B 78500 lbs thrust turbo fan; GE GENX-1B 78500 lbs thrust turbo fan
- Damage: No damage
- Flight: Part 121
- Operator: United Airlines Inc
- Registered owner: United Airlines Inc
- Airworthiness certificate: Standard, Transport
- Last inspection: Continuous airworthiness, December 11, 2022
- Departed: LAX, Los Angeles, CA
- Destination: VHHH, Hong Kong, PO
- Flight plan: IFR
- Equipment: ADS-B, Angle of attack indicator, Auto-pilot, Data recorder, Electronic flight bag or handheld device, Electronic multifunction display, Electronic primary flight display, Heads up display, Onboard weather, Satellite tracking device, Stall warning system

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 62; injuries: none; airline transport; airplane ratings: single-engine land, multi-engine sea; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review May 30, 2024; seat: left; flight hours: 22,000 total, 5,500 in this make and model, 9,300 as pilot in command, 240 in the last 90 days, 89 in the last 30 days, 15 in the last 24 hours
- Co-pilot; age 59; injuries: none; airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review June 26, 2024; seat: right; flight hours: 18,000 total, 700 in this make and model, 2,000 as pilot in command, 170 in the last 90 days, 90 in the last 30 days, 15 in the last 24 hours
- Other flight crew; injuries: none; airline transport; seat: rear; flight hours: 13,500 total
- Other flight crew; airline transport; seat: rear; flight hours: 15,948 total

## Weather

- Conditions: Instrument (IMC), Day

## Docket (6 files)

The files NTSB released with the investigation on September 3, 2025, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=199406. 6.0 MB in all.

- Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 10 pages, 1.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19146675&FileExtension=pdf&FileName=6120%20DMS_Redacted-Rel.pdf
- Flight crew statements (item 2, PDF, 5 pages, 219 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19147104&FileExtension=pdf&FileName=Flight%20Crew%20Statements-Rel.pdf
- Cabin crew statments (item 3, PDF, 2 pages, 82 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19146824&FileExtension=pdf&FileName=Cabin%20Crew%20Statements%20UAL%20152-Rel.pdf
- Ual weather summary (item 4, PDF, 7 pages, 687 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19147154&FileExtension=pdf&FileName=UAL152-Rel.pdf
- Flight data recorder - specialista��s factual report (item 5, PDF, 11 pages, 958 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18621312&FileExtension=pdf&FileName=FDR-Report_DCA25LA055_FINAL-Rel.pdf
- Flight data recorder - attachment 1 (FDR tabular data) (item 6, CSV, 2.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18620797&FileExtension=csv&FileName=FINAL-Attachment1_TabularData-Rel.csv

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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